Free Silica Research Articles

Transcriptomic profiling of lung fibroblasts in silicosis: Regulatory roles of Nrf2 agonists in a mouse model

Silicosis is an occupational disease caused by long-term inhalation of free silica, resulting in a significant global health burden. Its pathogenesis remains unclear, and there is no effective treatment. Proliferative and activated myofibroblasts play a key role in the development of silicosis. Traditional studies have focused on fibroblast proliferation and collagen secretion, neglecting their functional heterogeneity. With the advancement of omics research, more pathogenic fibroblast subgroups and their functions have been identified. In this study, we applied transcriptomics to analyze gene changes in primary lung fibroblasts during silicosis development using a mouse model. Our results indicate that DEGs are enriched in collagen secretion, ECM synthesis, leukocyte migration, and chemotaxis functions. Altered core genes are associated with immune cell recruitment and cell migration. Nrf2 agonists, known for anti-inflammatory and antioxidant properties, have shown potential therapeutic effects in fibrotic diseases. However, their effects on fibroblasts in silicosis are not fully understood. We used four common Nrf2 agonists to study gene expression changes in lung fibroblasts at the transcriptome level, combined with histopathological and biochemical methods, to investigate their effects on silicosis in mice. Results show that Nrf2 agonists can exert anti-silicosis fibrosis functions by downregulating genes like Fos and Egr1, involved in cell differentiation, proliferation, and inflammation. In conclusion, this study suggests that inflammation-related co-functions of fibroblasts may be a potential mechanism in silicosis pathogenesis. Targeting Nrf2 may be a promising strategy to alleviate oxidative stress and inflammation in silicosis.

Investigation on the current situation of occupational disease hazards in stone processing enterprises in Weihai City

Objective: To analyze the occupational disease hazards in stone processing enterprises in Weihai City to provide scientific basis for occupational disease prevention. Methods: From January 2021 to December 2022, 107 stone processing enterprises in Weihai City were selected to collect the detection status of occupational hazard factors in the workplace through on-site investigation and on-site monitoring of occupational hazard factors. The diagnostic reports on occupational diseases and suspected occupational diseases of 780 workers were collected through the Occupational Diseases and Hazard Factors Monitoring Information System of the Chinese Center for Disease Control and Prevention, the occupational health monitoring files of the occupational health examination institutions and the information data of the occupational disease diagnosis institutions. The differences between the measurement data were analyzed by Chi-square test or Fisher exact probability method. Results: 107 stone processing enterprises were mainly focused on granite processing, and the average free silica content in granite was 32.92% (12.78%-47.84%). The over-standard rate of silica dust was 0.31% (6/1920), and the over-standard rate of noise was 86.20% (1324/1536). Among them, the noise intensity of cutting position was the highest[120.5 dB (A) ]. The over-standard rates of noise in cutting, water grinding, dry grinding (polishing) and material preparation (forklift transportation) were 98.05%, 89.55%, 70.00% and 42.62%, respectively, and the differences were statistically significant (P<0.05). Among 780 workers, 31 cases (3.97%) of suspected silicosis were detected, and 13 cases (1.67%) were diagnosed with silicosis. 51 cases (6.54%) of suspected occupational noise deafness were detected, and 11 cases (1.41%) were diagnosed with occupational noise deafness. Conclusion: Silicon dust and noise in some positions of stone processing enterprises in Weihai City exceed the standard, and supervision should be strengthened, prevention and control measures should be implemented to protect the occupational health of workers.

Diatom silicon isotope ratios in Quaternary research: Where do we stand?

Silicon stable isotope ratios (expressed as δ30Si) in biogenic silica have been widely used as a proxy for past and present biogeochemical cycling in both marine and lacustrine settings, in particular for nutrient utilization reconstructions. Yet an analysis of publication trends suggests a significant decline in the application of δ30Si to Quaternary science questions in the last five years. At the same time as δ30Si proxy applications have decreased, we are learning more about its complexities: an expanding body of work is highlighting biases, caveats or complications involved in the application of δ30Si-based approaches to the sediment record. These include the demonstration of species-specific silicon isotope fractionation factors (i.e. ‘vital effects’) or the potential for Fe or other trace metals to influence silicon isotope fractionation. Others have inferred the potential of biogenic silica dissolution to alter an initial δ30Si value, or questioned the preservation of the initial δ30Si through early diagenetic processes more generally. Another challenge receiving more attention is centered around deconvolving a δ30Si-value into a signal reflecting biological productivity and a signal reflecting changes in the δ30Si of dissolved silicon driven by whole-system and/or circulation changes. Finally, a number of studies focus on analytical difficulties, especially during sample preparation related to achieving and demonstrating a contaminant free biogenic silica. These challenges lead us to posit that the Quaternary science community is moving away from silicon isotope proxies because they are losing confidence in their reliability and usefulness. Here, focusing on the diatoms – the dominant biosilicifiers in both lakes and the ocean – we synthesize progress in understanding nuances and caveats of δ30Si-based proxies in order to answer whether the fall-off in δ30Si-based Quaternary research is warranted. We suggest that with some simple steps that can be readily implemented, and with the closing of key knowledge gaps, there is no reason to believe silicon isotopes do not have a promising future in the Quaternary sciences.

Occupational Exposure to Silica Dust and Silicosis Risk in Chinese Noncoal Mines: Qualitative and Quantitative Risk Assessment.

Despite increasing awareness, silica dust-induced silicosis still contributes to the huge disease burden in China. Worryingly, recent silica dust exposure levels and silicosis risk in Chinese noncoal mines remain unclear. We aimed to determine recent silica dust exposure levels and assess the risk of silicosis in Chinese noncoal mines. Between May and December 2020, we conducted a retrospective cohort study on 3 noncoal mines and 1 public hospital to establish, using multivariable Cox regression analyses, prediction formulas of the silicosis cumulative hazard ratio (H) and incidence (I) and a cross-sectional study on 155 noncoal mines in 10 Chinese provinces to determine the prevalence of silica dust exposure (PDE), free silica content, and total dust and respirable dust concentrations. The qualitative risk of silicosis was assessed using the International Mining and Metals Commission's risk-rating table and the occupational hazard risk index; the quantitative risk was assessed using prediction formulas. Kaplan-Meier survival analysis revealed significant differences in the silicosis probability between silica dust-exposed male and female miners (log-rank test χ21=7.52, P=.01). A total of 126 noncoal mines, with 29,835 miners and 4623 dust samples, were included; 13,037 (43.7%) miners were exposed to silica dust, of which 12,952 (99.3%) were male. The median PDE, free silica content, total dust concentration, and respirable dust concentration were 61.6%, 27.6%, 1.30 mg/m3, and 0.58 mg/m3, respectively, indicating that miners in nonmetal, nonferrous metal, small, and open-pit mines suffer high-level exposure to silica dust. Comprehensive qualitative risk assessment showed noncoal miners had a medium risk of silicosis, and the risks caused by total silica dust and respirable silica dust exposure were high and medium, respectively. When predicting H and I over the next 10, 20, and 30 years, we assumed that the miner gender was male. Under exposure to current total silica dust concentrations, median I10, I20, and I30 would be 6.8%, 25.1%, and 49.9%, respectively. Under exposure to current respirable silica dust concentrations, median I10, I20, and I30 would be 6.8%, 27.7%, and 57.4%, respectively. These findings showed that miners in nonmetal, nonferrous metal, small, and open-pit mines have a higher I and higher qualitative silicosis risk. Chinese noncoal miners, especially those in nonmetal, nonferrous metal, small, and open-pit mines, still suffer high-level exposure to silica dust and a medium-level risk of silicosis. Data of both total silica dust and respirable silica dust are vital for occupational health risk assessment in order to devise effective control measures to reduce noncoal mine silica dust levels, improve miners' working environment, and reduce the risk of silicosis.

EVALUATION OF COMPATIBLE PROCESSING ROUTES USING THERMAL TREATMENT FOR UPGRADING OF MOPA MURO AND OBAN MASSIF MANGANESE DEPOSITS

The present study deals with evaluation and compatibility of processing routes using thermal treatment for upgrade of mopa muro and oban Massif manganese ore deposits. The study samples are characterized by XRD, XRF and SEM analysis. The results of SEM analysis show the micro-cracks in the thermally treated manganese sample, Mineralogical investigation shows that in the Mopa Muro manganese ore, most of the Manganese occurs in the silicate managenese mineral as in Almandine (Fe2+)3Al2(SiO4)3, Spessartine(Mn2+)3Al2(SiO4)3, Clinochlore (Al-Fe-SiO2-OH), Geothite FeO(OH),while the Oban Massif is rich in, Pyrolusite MnO2, Clinochlore (Al-Fe-SiO2-OH ), and Spessartine(Mn2+)3Al2(SiO4)3. The mineralogy of the two deposits also revealed that there is a Free Silica (Quartz) in abundant. The low content of sulphur and phosphorus is however within the requirement of the metallurgical grade manganese ore, while 44.08% and 42.07% of manganese (Mn) obtained for Mopa Muro and Oban Massif manganese ores respectively after all analysis indicate apparent inability of the ores meet the requirement of metallurgical grade manganese with values less than 66% recommended specification using thermal treatment.

Lung decellularized matrix-derived 3D spheroids: Exploring silicosis through the impact of the Nrf2/Bax pathway on myofibroblast dynamics

Silicosis is an occupational respiratory disease caused by long-term inhalation of high concentrations of free silica particles. Studies suggest that oxidative stress is a crucial initiator of silicosis fibrosis, and previous studies have linked the antioxidative stress transcription factor known as Nrf2 to fibrosis antagonism. Myofibroblasts play a pivotal role in tissue damage repair due to oxidative stress. Unlike physiological repair, myofibroblasts in fibrosis exhibit an apoptosis-resistant phenotype, continuously synthesising and secreting significant amounts of collagen and other extracellular matrices, which could be a direct cause of silicosis fibrosis. However, the relationship and mechanism of action between oxidative stress and myofibroblast apoptosis resistance remain unclear. In this study, a new 3D cell culture model using mice lung decellularised matrix particles and fibroblasts was developed, simulating the changes in myofibroblasts during the development of silicotic nodules. Western Blot results indicate that silica stimulation leads to increased collagen deposition and decreased apoptosis-related protein Bax and oxidative stress-related protein Nrf2 in the 3D spheroid model. Immunofluorescence experiments reveal co-localisation in their expression. In Nrf2 overexpressing spheroids, Bax exhibits significant upregulation. In the Nrf2 knockout spheroids, Bax is also significantly downregulated; after intervention with Bax inhibitors, a significant downregulation of Bax-induced apoptosis was also detected in the Nrf2-overexpressed spheroids. In contrast, Bax-induced apoptosis showed a significant upregulation trend in Nrf2-overexpressed spheroids after intervention with Bax agonists. The results demonstrate that the spheroid model can mimic the development process of silicotic nodules, and silica stimulation leads to an apoptosis-resistant phenotype in myofibroblasts in the model, acting through the Nrf2/Bax pathway. This research establishes a new methodology for silicosis study, identifies therapeutic targets for silicosis, and opens new avenues for studying the mechanisms of silicosis fibrosis.

FAP expression dynamics and role in silicosis: Insights from epidemiological and experimental models

Prolonged exposure to free silica leads to the development of silicosis, wherein activated fibroblasts play a pivotal role in its pathogenesis and progression. Fibroblast Activation Protein (FAP), as a biomarker for activated fibroblasts, its expression pattern and role in key aspects of silicosis pathogenesis remain unclear. This study elucidated the expression pattern and function of FAP through population-based epidemiological investigations, establishment of mouse models of silicosis, and in vitro cellular models. Results indicated a significant elevation of FAP in plasma from silicosis patients and lung tissues from mouse models of silicosis. In the cellular model, we observed a sharp increase in FAP expression early in the differentiation process, which remained high expression. Inhibition of FAP suppressed fibroblast differentiation, while overexpression of FAP produced the opposite effect. Moreover, fibroblast-derived FAP can alter the phenotype and function of neighboring macrophages. In summary, we revealed a high expression pattern of FAP in silicosis and its potential mechanistic role in fibrosis, suggesting FAP as a potential therapeutic target for silicosis.

Cleaning mechanisms during post chemical mechanical polishing (CMP) using particle removal of surfactants via a citric acid-based solution

With the development of circuit integration technology, the requirements for defects in copper interconnects have become more stringent. The residual SiO2 particles on the copper surface can seriously affect circuit performance and require more efficient and thorough removal. This article investigates the effects of a novel cleaning solution composed of citric acid (CA), alkyl polysaccharide glycosides (APG1214), and dodecylbenzene sulfonic acid (LABSA), aimed at improving the removal efficiency of SiO2 and maintaining the integrity of copper surface. The optimal concentrations of APG1214 and LABSA were determined through contact angle and surface tension analysis. It was found that when APG1214 (2000 ppm) and LABSA (1000 ppm) were combined in a 3:2 vol ratio in CA solution (0.6 wt%), the highest particle removal efficiency (99.5 %) could be achieved while minimizing surface roughness. The results of scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirmed these findings. Combining quantum chemical calculations, new insights into the mechanism of action of different components in clean solutions have been proposed: 1. Similar to CA, LABSA and APG1214 demonstrate a strong affinity for copper, synergistically facilitating the cleavage of Cu-Si bonds. 2. Alternating adsorption of LABSA and APG1214 on free silica particles prevents their re-adsorption onto copper surfaces. 3. Furthermore, their orderly adsorption on copper mitigates the corrosive chelation effect of CA, providing a protective mechanism. These findings are pivotal for the development of advanced, multifunctional cleaning solutions.

Bioinformatics-based dynamics of cuproptosis -related indicators in experimental silicosis

Pneumoconiosis is one of the most serious occupational diseases worldwide. Silicosis due to prolonged inhalation of free silica dust during occupational activities is one of the main types. Cuproptosis is a newly discovered mode of programmed cell death characterized by the accumulation of free copper in the cell, which ultimately leads to cell death. Increased copper in the serum of silicosis patients, suggests that the development of silicosis is accompanied by changes in copper metabolism, but whether cuproptosis is involved in the progression of silicosis is actually to be determined. To test this hypothesis, we screened the genetic changes in patients with idiopathic fibrosis by bioinformatics methods and predicted and functionally annotated the cuproptosis-related genes among them. Subsequently, we established a mouse silicosis model and detected the concentration of copper ions and the activity of ceruloplasmin (CP) in serum, as well as changes of the concentration of copper and cuproptosis related genes in mouse lung tissues. We identified 9 cuproptosis-related genes among the differential genes in patients with IPF at different times and the tissue-specific expression levels of ferredoxin 1 (FDX1) and Lipoyl synthase (LIAS) proteins. Furthermore, serum CP activity and copper ion levels in silicosis mice were elevated on days 7th and 56th after silica exposure. The expression of CP in mouse lung tissue elevated at all stages after silica exposure. The mRNA level of FDX1 decreased on days 7th and 56th, and the protein level remained in accordance with the mRNA level on day 56th. LIAS and Dihydrolipoamide dehydrogenase (DLD) levels were downregulated at all times after silica exposure. In addition, Heatshockprotein70 (HSP70) expression was increased on day 56. In brief, our results demonstrate that there may be cellular cuproptosis during the development of experimental silicosis in mice and show synchronization with enhanced copper loading in mice.

Exploration of detection methods for free silica with different crystal forms in dust

Objective: To investigate the differences and applicability of free silica detection methods of different crystal forms in dust, and to provide a basis for the selection of various methods. Methods: From December 2021 to June 2022, dust samples from 20 enterprises in different industries in 18 cities in Henan Province were randomly selected as the investigation objects. X-ray diffraction (XRD) method was used to analyze the samples and classify the samples. Based on GBZ/T 192.4-2007 "Determination of Dust in the Air of Workplace-Part 4: Content of Free Silica in Dust", pyrophosphate method and infrared spectrophotometry were used for quantitative determination. The measured results were analyzed by paired sample t test to evaluate the advantages and disadvantages of the two methods and their applicable scope. Results: The XRD results of 20 dust samples could be divided into α, β, γ crystal types and the mixed type of α and γ. There was no significant difference between pyrophosphate method and infrared spectrophotometry (P=0.180). The pyrophosphate method results of β, γ and α, γ mixed crystalline free silica were significantly higher than those of infrared spectrophotometry, and the difference was statistically significant (P<0.001) . Conclusion: Pyrophosphate method and infrared spectrophotometry are suitable for α-type free silica, while pyrophosphate method is suitable for β, γ and α, γ mixed crystalline free silica.

Forsteritic olivine in EH (enstatite) chondrite meteorites: A record of nebular, metamorphic, and crystal‐lattice diffusion effects

AbstractThe occurrence of forsteritic olivine in EH enstatite chondrites is indicative of bulk disequilibrium. In MgO‐rich magmatic systems, forsterite can either crystallize as a liquidus phase or be produced during peritectic melting of enstatite. Because diffusion of divalent cations through forsterite is relatively rapid, it records peak melting (i.e., chondrule‐forming events) and is also sensitive to subsequent metamorphism in the EH chondrite parent body. Here, we report the major and minor element geochemistry of olivine in EH chondrites across petrologic types 3 and 4. In all cases, olivine meets the technical definition of forsterite (&gt;90 mole% Mg2SiO4). For unequilibrated EH chondrites, minor elements identify CaO‐Al2O3‐TiO2‐rich (refractory forsterite), MnO‐rich (“LIME” forsterite), and FeO‐bearing (forsteritic olivine) endmember components, the latter with Cr2O3‐rich and Cr2O3‐poor varieties. At higher petrologic type, minor element concentrations become restricted and compositions approach pure forsterite, while grain sizes reduce strongly with peak metamorphic temperatures. These changes reflect diffusive equilibration with enstatitic groundmass and dissolution reaction with free silica. The global geochemical distribution of forsteritic olivine in EH chondrites is, perhaps unexpectedly, more similar to those in low‐FeO type I chondrules and associated objects in carbonaceous chondrites (CCs), rather than equivalent objects in ordinary (H, L, LL), low‐FeO (or HH), or Kakangari (K) chondrites. Among achondrites, there is similarity between pure forsterite in aubrites and EH4 chondrites arising due to subsolidus equilibration in both settings, while Cr2O3‐poor forsteritic olivine in EH3 and CCs is similar to magnesian xenocrystic olivine in angrites. This might reflect CaO‐rich and SiO2‐poor magmatic sources across multiple early solar system reservoirs.

Stone mining work and dust pollution in Birbhum district, West Bengal, India.

Dust pollution is common in Indian roads and several industrial settings (including mines) that affects human health. Identification and characterization of the dust particles in the mining area is essential for knowing the properties of the dust that effectively causes ailments to humans, particularly among workers those who are working in unorganized industrial settings. The present study aimed to determine the level of dust pollution and to know the size and characterize the dust particles in the Pachami-Hatgacha stone mine areas of Birbhum district, West Bengal, India. Dust samples were collected and analysed for Dynamic Light Scattering (DLS) to determine the size and shape of the particles, Fourier Transform Infrared Spectroscopy (FT-IR) to determine the free silica content, and X-ray Florence (XRF) analysis for quantitative estimation of components in the sample. All the analyses were done following standard instrumentation and techniques. The size of the dust particles was much less (ranges 101-298nm) than the size of respirable particles (2500nm). Those were mostly generated as well as precipitated during peak working hours of the day. Presence of considerable amounts of silica was confirmed by the FT-IR (strong and broad band at 1000cm-1) and XRF analysis (76.85% SiO2). Exposure to these dust particles may cause severe health impairments. Therefore, interventions like wet drilling and blasting, sprinkling of water during peak working hours, and awareness of use of personal protective devices among workers are required to reduce the risk and hazards associated with dust pollution to the health of miners and inhabitants around the mines.

Assessment of Microsilica as a Raw Material for Obtaining Mullite–Silica Refractories

The possibility of using microsilica in the production of mullite–silica refractories was assessed. The chemical and mineralogical compositions of the raw materials, refractory Arkalyk clay and microsilica, were studied. It has been found that primary mullite and quartz formation occurs due to dehydration of kaolinite with the formation of intermediate metakaolinite. The introduction of alumina and microsilica into the charge composition promotes the formation of secondary mullite due to the interaction of aluminum oxide and highly dispersed chemically active microsilica. Free silica in compositions undergoes polymorphic transformations with the formation of cristobalite and tridymite. Mullite–silica refractories with an open porosity of 21%, a compressive strength of 42 MPa, and a thermal deformation temperature under the load of 0.2 MPa–1350 °C were obtained.

Inhibition of the ITGB1 gene attenuates crystalline silica-induced pulmonary fibrosis via epithelial-mesenchymal transformation.

Silicosis is a systemic disease caused by long-term exposure to high concentrations of free silica dust particles in the workplace. It is characterized by a persistent inflammatory response, fibroblast proliferation, and excessive collagen deposition, leading to pulmonary interstitial fibrosis. Epithelial interstitial transformation (EMT) can cause epithelial cells to lose their tight junctions, cell polarity, and epithelial properties, thereby enhancing the properties of interstitial cells, which can lead to the progression of fibrosis and the formation of scar tissue. Integrin 1 (ITGB1) is considered an important factor for promoting EMT and tumor invasion in a variety of tumors and also plays an important role in the progression of fibrotic diseases. Therefore, ITGB1 can be used as a potential target for the treatment of silicosis. In this study, we found that silica exposure induced epithelial-mesenchymal transformation in rats and that the expression of integrin ITGB1 was elevated along with the EMT. We used CRISPR/Cas9 technology to construct integrin ITGB1 knockdown cell lines for in vitro experiments. We compared the expression of the EMT key proteins E-cadherin and vimentin in the ITGB1 knockdown cells and wild-type cells simultaneously stimulated by silica and detected the aggregation point distribution of E-cadherin and vimentin in the cells using laser confocal microscopy. Our results showed that ITGB1 knockout inhibited the ITGB1/ILK/Snail signaling pathway and attenuated the EMT occurrence compared to control cells. These results suggested that ITGB1 is associated with silica-induced EMT and may be a potential target for the treatment of silicosis.

Availability of Silica in Dusts at different operations locations in Limestone Quarry in Ewekoro, Nigeria

The dusts from mines and quarries have been reported to induce respiratory problems among mineral workers. This study was carried out to investigate the availability of free silica in the dust from different parts of the quarry with different activities. The blasted, boreholes and stacked sites were investigated. The collected dust was analyzed using an X-Ray analyzer. The result shows that the highest free silica content (mean of 22.279%) was found in dusts from borehole, followed by blasted parts (17.195%). The stacked shows the least mean (7.566%). The statistical analysis carried out on the result using SPSS software shows that there is statistical independence of the dust from different sections of the quarry, meanwhile the values of the means are environmentally significant. The recommendations were made on how to control the negative effect of the free silica in every aspect of the quarry with emphasis on borehole drilling section.

Lung Function Indices among Marble Workers with Age Matched Healthy Individuals in Lahore

Background: Marble dust predominantly comprises of free silica which is a principal constituent of Earth’s crust. Production of toxic substances, chemicals, and respirable dust in marble industry offers an occupational threat to the workers. Free silica dust is generated during quarrying, grinding cutting and polishing of marble and is responsible for occupational pulmonary diseases. Objective: This study was conducted to compare pulmonary function test results among the workers of marble industry and healthy persons of same age in district, Lahore. Study Design: Cross-sectional study. Settings: Study was conducted in marble workshops workers, located in Township area College Road, Institute of Public Health, Lahore Pakistan. Duration: Six months from 05 May 2021 to 04 August 2021. Methods: A cross-sectional study was conducted among 225 individuals. Forty-five male persons, each were selected from cutting, grinding and polishing sections along with office workers from the marble workshop. Forty-five age matched healthy individuals selected from the same community. After getting approval from the Institutional Review board, the data was collected in a pretested standardized questionnaire after taking informed written consent by the respondents. Lung function tests were conducted by a Spiro Lab Spirometer which included forced vital capacity, forced expiratory volume in one second and ratio of forced expiratory volume to forced vital capacity. Results: The mean years of work experience of respondents was 11.58 ±5.92 and that of non-exposed healthy individuals was 11.23±5.32 years. A significant relationship of marble dust and deranged pulmonary function tests (p-value≤0.001) was noted which was normal in case of non-exposed individuals. Duration of work in marble industry and age in years had significant relationship with reduction in pulmonary function tests (p- value&lt;0.001 in each). About 83 (46%) marble workers working in different sections had reported abnormal spirometry as compared to non-exposed individuals (p-value&lt;0.001). Conclusion: According to the current study, individuals who had worked in the marble industry for more than 15 years had a steady reduction in their lung function indices, which ultimately had a detrimental effect on their health and when compared to healthy individuals of the same community, marble workers' pulmonary function tests showed significant impairments.

Feasibility evaluation of the use of mud residue from marble shop as soil remineralizer

Brazil is a major producer of dimension/ornamental stones, with a great diversity of raw materials. The sawing process transforms 20 to 30% of the extracted block into powder, with the generation of fine waste around 800,000 t/year. An alternative to reusing this waste is its application as a source of nutrients for the soil. This study evaluated the potential use of mud residue from a marble shop located in João Monlevade, Minas Gerais, as a remineralizer, based on fertility, mineralogical and chemical analysis performed by X-ray diffraction and X-ray fluorescence. For fertility, pH in CaCl2 0.01 mol L-1, organic matter, aluminum saturation, potential acidity, sum of bases, cation-exchange capacity, base saturation, macro and micronutrients were determined. The studied residue has free silica, the sum of basis, and K2O content in the range established by MAPA to be certified as a remineralizer. The sample contains 6.7% phyllosilicates, a source of faster K availability, and 19.4% K-feldspar, a slow-release source. Results described in this study indicate that residue can be a promising, efficient, and low-cost alternative to improve soil fertility.

Patterns in medical surveillance of workers exposed to lung carcinogens

Abstract One of the most common causes of lung cancer is exposure to occupational carcinogens. Free silica, diesel exhaust fumes, dyes, radon and with asbestos at the top of the list, differ by percentage according to the predominant professional activities in each country. The occupational health doctor is directly involved in the surveillance of the exposed worker, during work or post exposure, in the diagnosis and reporting of occupational cancers. Efficient screening followed by reporting and monitoring cases of occupational lung cancer and, last but not least, reintegration into professional activity are important steps in the medical surveillance of the worker exposed to occupational lung carcinogens. Standardised information collected at the level of occupational exposure monitoring systems, separated by carcinogen category and profession, may form the basis of control and prevention plans. Harmonising medical surveillance at European and global level can lead to a decrease in the incidence and mortality of work-related lung cancer.

Fermented cordyceps powder alleviates silica-induced pulmonary inflammation and fibrosis in rats by regulating the Th immune response

BackgroundSilicosis is an important occupational disease caused by inhalation of free silica and is characterized by persistent pulmonary inflammation, subsequent fibrosis and lung dysfunction. Until now, there has been no effective treatment for the disease due to the complexity of pathogenesis. Fermented cordyceps powder (FCP) has a similar effect to natural cordyceps in tonifying the lung and kidney. It has started to be used in the adjuvant treatment of silicosis. This work aimed to verify the protective effects of FCP against silicosis, and to explore the related mechanism.MethodsWistar rats were randomly divided into four groups including the saline-instilled group, the silica-exposed group, the silica + FCP (300 mg/kg) group and the silica + FCP (600 mg/kg) group. Silicosis rat models were constructed by intratracheal instillation of silica (50 mg). Rats in the FCP intervention groups received the corresponding dose of FCP daily by intragastric gavage. Rats were sacrificed on days 7, 28 and 56 after treatment, then samples were collected for further analysis.ResultsFCP intervention reduced the infiltration of inflammatory cells and the concentration of interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and transforming growth factor-β1 (TGF-β1) at days 7, 28, 56, and decreased the expression of collagen, α-smooth muscle actin (α-SMA) and fibronectin (FN) at days 28 and 56 in the lung of silicosis rats. FCP also decreased the immune response of Th1 and Th17 at days 7, 28, 56 and inhibited the enhancement of the Th2 response at day 56.ConclusionsFCP intervention could alleviate silica-induced pulmonary inflammation and fibrosis, the protective effect may be achieved by reducing Th1 and Th17 immune responses and inhibiting the enhancement of the Th2 response.

Electrochemical Oxygen Evolution from Metal Oxides Using Perovskite Anodes Towards Lunar Resource Utilization

In-situ resource utilization (ISRU) has been proposed for realizing sustainable lunar development. One of the representative resources on the Moon is lunar regolith, which covers the lunar surface. The chemical composition of lunar regolith resembles the constituents of the Earth: silica (SiO2) is the most abundant oxides in the lunar regolith. Silicon, which can be produced by silica reduction, will be the material for solar cells, and oxygen is essential for manned space exploration. Enormous amounts of silicon and oxygen will be obtainable on the Moon without transportation from the Earth by establishing silicon reduction methods without consumables. However, the conventional silica reduction method consumes vast amounts of carbon, which cannot be mined on the Moon.For realizing carbon free silica reduction method consistent with the concept of ISRU, molten salt electrolysis processes using perovskite anodes has been researched. In this method, the silica dissolved in molten salts is electrolyzed using voltage with passage of direct current through electrodes, which generate oxygen gas and silicon by the electrochemical process. The perovskite oxides have high electrical conductivity and oxidation resistance. Therefore, the perovskite anodes have been expected as oxygen generation inert anodes.In this study, we report the characteristics of perovskite-type anodes for oxygen generation measured in the electrolysis experiments. In molten fluoride containing silica at a temperature over 500℃, the measured cyclic voltammograms with a perovskite-type anode show drastically increases of current density at 2.6 V vs K+/K, which was approximately same to the oxygen generation potential in the previous molten salt electrolysis result without the perovskite anodes. The characteristics of perovskite-type anodes for oxygen generation will be discussed from the results of electrochemical measurements and chemical analysis using XRD, SEM, EDX, and ICP-AES analysis.